Developing a database of Australian grasshopper occurrences from historic field survey notebooks spanning 54 years (Orthoptera: Acrididae, Morabidae, Pyrgomorphidae, Tetrigidae)

Abstract

The baseline distribution data for all species of a given group in a region can provide fundamental insights into biogeographic questions about historic patterns of species richness, population trends and extinction. Grasshoppers are one major group of insects for which a continent-wide perspective on their geographic distribution can be obtained. This is because they were extensively surveyed in Australia for 54 years (1936–1989) as part of Commonwealth expeditions to obtain specimens for the Australian National Insect Collection (ANIC). Field notebooks recorded from those surveys, under the direction of ANIC curator and director K. H. L. Key, form the principal source of historic distribution records for grasshoppers in Australia. We digitised all the 223 notebooks (2486 pages) and transcribed all the field trips conducted in Western Australia (WA) and Tasmania (47 notebooks, 590 pages). We then carefully geocoded all sampling sites of the transcribed notebooks, following the odometer readings and descriptions of routes from a suitable reference point using historic topographic maps and Google Earth. In total, we extracted 8975 geographic coordinates for 477 species having a confirmed or putative taxonomic name at genus or species level (only 170 of these species have been formally described). We found that species richness varied spatially, with highest richness in arid interior and north of WA. Historic grasshopper surveys were non-randomly distributed across both WA and Tasmania with the highest survey intensity around coastal regions. Variation was observed among surveyors in terms of the number of species detected per site, between-site distance and the season of survey being conducted. Overall, however, the dataset is among the most comprehensive continent-wide surveys of Australian invertebrates and will greatly facilitate future work on their ecology, biogeography, conservation and responses to environmental change.